Arc chute defining two alternate arc paths



Aug. l2, 1952 H. v. NYE

ARC CHUTE DEFINING TWO ALTERNATE ARC PATHS 2 SHEETS-SHEET 1 Filed Jne 1l, 1949 illrllildllllllln qdaagaaaaa W m MM m H. V. NYE

ARC CHUTE DEFINING TWO ALTERNATE ARC PATHS A ug. 12, 1952 2 SHEETS--SHEET 2 Filed June 11, 1949 Patented Aug. 12, 1952 ARC `CHUTE DEFINING TWO ALTERNATE ARC PATHS Henry v. Nye, West Allis, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application June 11, 1949, serial No. 98,527

This invention relates to circuit interrupting devices and more particularly toV arc extinguishing means for use in connection therewith.

In the construction and operation of circuit interrupters, it is frequently necessary to provide means for extinguishing quickly the arc which is drawn between separable arcing contacts. This arc is usually vblown by blowout means, such as a magnetic blowout coil or an air blast, into an arc chute which' is arranged to quench the arc by lengthening'it, cooling it, or a combination of both. L

Arc chutes having spaced insulating plates to lengthen the are or squeeze the arc into narrow slots are Well known. Arc chutes which consist of spaced metallic plates or their equivalent which break the arc into a number of small arc segments in series and move the arc rapidly across cooling surfaces, are also well known. It has also been proposed to use spaced metal pins or bars for the purpose of cooling' and quenching the arc. The spacing and arrangement of the arc quenching elements, however, have not been entirely satisfactory with the result that arc interruption has not been reasonably consistent except for arc chutes having a large aggregate mass of cooling material.

In accordance with the invention claimed an are chute is provided adjacent a pair of arcing contacts for receiving the arc at one end thereof and in the majority of cases exhausting the arcing products at the other end thereof.' The arc chute employs an arcextinguishing device which provides a first arc path which breaks the arc into a number of small serially connected arc segments. An insulating barrier may be mounted adjacent the first arc path for lengthening and cooling the arc. A second arc path is provided for further elongating and cooling the arc and for placing the arc, after a current zero, in series with a current limiting resistor.

It is, therefore, one object of the present invention to provide a new and'improve'd'arc interrupting device.

Another object of the invention is to provide a new and improved arc interrupting device that rapidly extinguishes a high voltage power arc within a comparatively small space.

A further object of the invention is to provide a plurality of arc paths to break the arc into a number of arc segments. extend and cool the arc, and rapidly extinguish the arc within apredetermined period of time. n

Objects and advantages other than those above set forth will be apparent fromthe following de- 9 Claims. (Cl. ZOU- 144) scription when read in connection with the accompanying drawings in which:

Fig. 1 is a diagrammatic view partly in cross section of a magnetic blowout type circuit breaker embodying the present invention; and

Fig. 2 is a diagrammatic view partly in cross section of a fluid blast circuit breaker embodying a variation of the invention illustrated in Fig. 1.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a magnetic blowout type of circuit breaker including as elements thereof a pair of terminal studs 6 and 1 for connecting the circuit breaker to line conductors (not shown). Although in general, circuit breakers of the type considered in Figs. 1 and 2 are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure is shown in the drawings and the circuit breakers will be described in detail as if they were of the single pole unit type.

The circuit interrupter or kbreaker in Fig. 1 comprises essentially means for opening the circuit to form the interrupting arc and an arc extinguishing structure. Speciiically, the circuit opening means comprises relatively fixed contacts 8 and 9, a fixed arcing contact I0, and a movable arcing contact II. Arcing contact II is mounted on a lever 28 which is pivotally mounted at I2 on an extension I3 of the circuit breaker stud 6 and is operated by means of a reciprocally movable rod I4. The operating rod I4 is suitably connected to an actuating mechanism (not shown) for operating the movable contact between closed and open circuit positions. Fig. 1 illustrates the movable contact I I in its open circuit position. The arcing contacts are electrically connected to the lower ends of terminal studs 6 and 1. Accordingly, when the breaker is connected in series in a power circuit and the arcing contacts are separated, an arc may form across the gap indicated.

For the purpose of interrupting this power arc, an arc extinguishing structure, such as an arc chute I5 may be mounted so as to receive the power arc which is under the iniiuence of the magnetic blowout means. The arc chute preferably is disposed directly above the arcing contacts, as shown, when the blowout means act upward, but may be mounted in any other suitable location when the blowout means act in other directions. The switch or arcing contacts and the magnetic blowout structure can assume any preferred form and comprise no part of the present invention so that a brief description will be sumcient. The magnetic blowout means comprises a core il, poles i8, and a coil iii which is electrically connected to the terminal stud 'i and to an arc runner l so that the arc current (as the arc travels along the runner) ilows through the blowout coil in a manner well known in the art. f

Normally the current is carried in the closed circuit position of the breaker by the spring biased contact S. As the movable arcing contact |l is actuated to open circuit position, current is shuntelongated and reduced in cross section as the arc ed from iixed contact 8 to fixed contact Si, to Y xed arcing contact it. As the arc is drawn by the movable arcing contact l the arc terminal on arcing contact iii is transferred to arc runner la which is usualy an extension armor the fixed arcing contact i0. As the movable arcing contact il reaches its full opening stroke the arc terminal transfers from ythe movable arcing contact to an arc runner 2d which directs thearc into the arc chute i5. The arcing contact iii and the arc runner i9 are electrically connected in series with the blowout coil i5 and stud l. Accordingly, the blowoutcoil is already energized at the inception ci the arc interruption to influence the arc in a well known manner, i. e. to drive it into the arc chute i5 .inan ever expanding loop. It will be apparent to one skilled in the art that the blowout eld can be utilized. in the most eilicientV manner by disposing the iron pole i8 so as to cooperate with 'the blowout coil in the conventional manner at lthe outer sides of the arc chute.

In accordance with the invention, the arc chute i5 comprises a new and improved structure for interrupting the arc by lengthening, cooling, and increasing the resistance of the arc stream. The arc extinguishing structure may have walls including two end walls 2|, 22 composed of arc resisting material,l such' as, for l example, an asbestos compound or asuitable arc resisting ceramic material.

For the purpose of greatly increasing the interrupting capacity and eiiiciency or the, arc chute a rst group of metallic members, which for example may be a row of copper rodsy or pins 23, are disposed between end walls 2|, 22 so that the pins extend transverselyto the direction oi movement of the arc. Pins 23 form a irst arc path through the strongest part of the magnetic field of the magnetic blowout means. A plurality of partitions 24 kforming an insulating barrier may be disposed between the side walls 2|, 22' to extend transverselyV of the arc with one end thereof disposed adjacent the pins 23 and the other end extending toward the exhaust end or arc chute i5. A second group of metallic members, which for example may also be of a row of copper rods or pins` 25, is disposed between the side walls 2|, 22 so that the pins extend transversely to the direction of movement of the arc and adjacent the exhaust end of the partitions 25. Pins 25 provide a second or alternative path for the arc to travel and may comprise a plurality of pins greater in number than those deiining the rst arc path. A resistor 26 may be connected to' at least one or" the pins 25 and to the end of the magnetic blowout coil i5 connected to contact l0, thus forming an arc path through a current limiting resistor for aiding arc extinguishment.

As shown, an insulating baiiie 2l, comprising a plurality of strips of a suitable arc resisting insulating material, such as asbestos board, is arranged near the exhaust end of the arc chute |5.

moves outward through the arc passage under the iniiuence of the blowout means. Partitions A 24, forming an insulating barrier, may be used to further extend and cool the arc.

Y If the arc restrikes after the iirst current zero,

it will have a tendency to follow a second alternative arc path formed by pins 25 and builds up through resistor 26 which is connected in series therewith. The second arc path may comprise a plurality of pins greater .in number than those forming the rst arc path. The arc segments between pins 25 are further elongated, attenuated, cooled and rapidly extinguished.

Fig. 2 illustrates a iiuid blast circuit breaker structure embodying the new and improved arc extinguishing device. The circuit breaker includes as a constructive element thereof a reservoir 3| constituting a source or supply of fluid under pressure which will be assumed herein to be compressed air ,supplied from a suitable compressor (not shown).

The circuit breaker comprisesA a fixed arcing contact 32 and a cooperating movable arcing contact 33 connected in an electric circuit through terminal studs 34` and 35. The arcing contacts 32 and 33 are mounted to engage within a tubular arcing chamber 36 which is axially aligned with and supporting an arc chute 3l. The arcing chamber 36 is axially aligned with and supported by a hollow insulator 38A which provides a connection between reservoir 3|v and arcing chamber 36 through a suitable blast valve 39 for the purpose of directing a blast of arc extinguishing nuid under pressure between the arcing contacts and through the arcingv chamber 38.

The operation or blast valve 39 is correlated with thatv of a contact actuating fluid operated motor 4|4 to boost the action of the contact operating motor, thereby increasing the initial speed of contact separation. Motor 4| and' particularly piston rod 42 rotates shaftl 43 counterclockwise and in turn actuates connecting rod 44 to separate the. arcing contacts 32 and 33. The blast valve 39 through a series of lever arms 45', 4B, and connecting rods'41, 48 boosts the action of motor 4| `by'act'uating shaft 43 countercloclcwise in conjunction with motor 4|. This. type of booster meansL for fluid blast circuit breakers is more fully described' and claimed in U. S. Patent No. 2,597,126, granted` May 20', 1952 upon the application of Ira W. Paterson. K Arc chute 31 comprises a structure similar to that illustrated in Fig. l, but adapted to t into an air blast circuit breaker. The arc chute has walls including end walls 5|, 52 `composed of are resisting material, an arc runner 53 mounted within arc chute 31 and associated with the movable arcing contact 33, arr arc runner 54' mounted within an arc chute 3l and associated with xed arcing contact 32, la rst group of metallic members or pins55 forming a first arc path, and a second group of metallic members or pins 56 forming a second or alternative arc path. rlhe metallic members orv pins 55 and 56 are similar to pins 23 and 24 of Fig. 1 and are mounted within arc chute 31 'to extend transversely to the direction of movement of the are. A resistor 51 may be connected to at least one of the pins 56 and to the conductive structure of the fixed arcing contact 32, thus forming an arc path through a current limiting resistor for aiding arc extinguishment. As shown, an insulating baffle 58 comprising a plurality of strips of suitable arc resisting material is arranged to form a barrier near the exhaust end of the arc chute 31 for retaining the arc within the chute but permitting suitable exhausting of the arc gases.

Upon separation of the arcing contacts 32 and 33 by the joint operation of the contact actuating motor 4l and the blast valve booster means.

a blast of air under pressure drives` the arc into the arc chute 31 and against the first group of pins 55 forming the first arc path. Here the arc is broken up into segments which are elongated, attenuated, and cooled. After a current zero if the arc restrikes it is driven to the second group of pins 56 forming the second or alternative arc path where the arc current builds up through a resistor 51 which is connected in series therewith. Here the arc is broken up into a greater number of segments and is further elongated, attenuated, cooled, and rapidly extinguished.

Although but two embodiments of the present invention have been illustrated and described, it

vwill be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. An electric circuit interruptei` comprising a stationary arcing contact, a cooperating movable arcng contact, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end thereof, a source of fluid under pressure for imparting to the arc a movement in a predetermined direction through said arc chute, a current limiting resistor, and an arc extinguishing means within said chute comprising spaced metallic members mounted therein in two consecutive rows extending transversely of the arc for providing a first arc path and a second arc path in series with said resistor, at least a part of said members of said second arc path being aligned with the members of said first arc path in the said direction of movement of the arc through said chute, the distance between said arc paths being greater than the spacing between members of said arc paths for controlling the movement of the arc, and baffle means arranged adjacent the metallic members of said second arc path and extending toward the exhaust end of said chute for confining said arc.

2. An electric circuit interrupter comprising means for drawing an arc and an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said chute comprising a rst group of metallic members mounted therein to extend transversely of the arc for providing a rst arc path, insulating barriers mounted to extend transversely of the arc each having one end thereof disposed adjacent a different one of said first group of metallic members and the other end thereof extending toward the exhaust end of said chute for elongating said arc,rand asecond group of metallic -members mounted adjacent said other ends of said barriers for providing a second arc path vwhich divides each arc section between adjacent barriers into a predetermined number of arc sections.

3. An electric circuit interrupter comprising means for drawing an arc and an arc chute for receiving the are at one end thereof and exhausting the arc products at the other end, said chute comprising a first group of metallic members mounted therein to extend transversely of the arc for providing a first arc path, insulating barriers mounted to extend transversely of the are each having one end thereof disposed adjacent a different one of said first group of metallic members and the other end thereof extending toward the exhaust end of said chute for elongating said arc, and a second group of metallic members mounted adjacent said other ends of said barriers for providing a second arc path which divides each arc section between adjacent barriers into a predetermined number of serially connected arc sections.

4. An electric circuit interrupter comprising means for drawing an arc and an arc chute for receiving the arc at one end thereof and exhaustingthe arc products at the other end, said chute comprising a first group of metallic members mounted therein to extend transversely of the arc for providing a first arc path, insulating barriers mounted to extend transversely of the arc each having one end thereof disposed adjacent a different one of said first group of metallic members and the other end thereof extending toward the exhaust end of said chute for elongating said are, and a second group of metallic members mounted adjacent said other ends of said barriers for providing a second arc path which divides each arc section between adjacent barriers into two smaller arc sections.

5. An electric circuit interrupter comprising means for drawing an arc and an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said chute comprising a first group of metallic members mounted therein to extend transversely of the are for providing a first arc path, insulating barriers mounted to extend transversely of the arc each having one end thereof disposed adjacent a different one of said first group of metallic members and the other end thereof extending toward the exhaust end of said chute for elongating said arc, and a second group of metallic members mounted adjacent said other ends of said barriers for providing a second are path which divides each arc section between adjacent barriers into a predetermined number of are sections, said barriers being separated from all said metallic members by air gaps.

6. An electric circuit interrupter comprising means for drawing an arc and an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said chute comprising a first group of metallic members mounted therein to extend transversely of the arc for providing a first arc path, insulating barriers mounted to extend transversely of the arc each having one end thereof disposed adjacent a different one of said first group of metallic members and the other end thereof extending toward the exhaust end of said chute for elongating Said arc, a second group of metallic members mounted adjacent said other ends of said barriers for providing a second arc path which divides each are section betweenadjacent barriersinto -a predetermined number of arc sections, and a baffle structure comprising a plurality of 'insulating plates extending transversely of the arc mounted within the exhaust end of said arc chute for confining said arc.

7. An electric circuit -interrupter comprising means for drawing an arc and-anarc chute -for receiving the -arc atene-end lthereof #and exhausting the arc products `-at the other end, magnetic blowout means `for driving the arc into vsaidchute and Ltoward the exhaust end thereof, `and a -current limiting resistor, Asaid ychute 'comprising `a rst group of metallic members vmounted therein to extend transversely of the arc for providing a irst arc path, insulating barriers mounted vto extend transversely of Lthe arc each having one end thereof disposed adjacent va different one of said first grouplof metallic -members and .the

Vother end thereof extending Vtoward the exhaust end of said chute ffor elongating said arc, and a second group of rinetallic members mounted adjacent said other ends of said barriers for -providing a second arc path in series with said resistor which divides each-arcsection between a d jacent barriers linto fa predetermined 'number of arc sections.

f8. An electric circuit interi-'unter comprising means for drawing anarc, an are `chute 'for receiving the arc at one end-thereof and exhausting the arc products'at the otherend, means for imparting to the arc *a 'movement in -a predetermined direction through Vsaid -arc chute, said chute containing spaced metallic `members mounted therein in 'two consecutive -rows ex` tending `transversely of the larc for providing a rst arc path and a second arc path, at least a part of said vrnernbersof said second arc path being aligned with the members of 'said rst arc path in the said direction of movement ofthe arc through said arc chutefsaidothermembers of said second arc path dividing 'each arc-sectionbetween said members 'of said iirst Yarc path Ainto a `predetermined number of :arc sections, a

current limiting lresistor iin series Withsaid second -arc path, and a Abaiileistructure |comprising 'a pluralityofiinsulating platesrm'ounted within'the exhaust end of said chuteor con'ningrsaid arc.

v9. An electric circuit interrupter comprising `means Vfor drawing an arc Aand ian 'arc .chute Vfor receivingthe arcat one end thereof and exhaustin'g the arc products ,at the :other vend, said .chute comprising a rst .group of .metallic members mounted therein to :extend vtransversely of the varc for providing V'a yrstarc Lpath,iinsulating :barriers moun-tedt'oextend transversely :of the arc each having one end thereof disposedjadjacent a different one of said `first vgroup pf metallic members and the other `end thereof extending 'toward the exhaust end Tof Vsaid .chute for elongating said arc,fandfa-sec`o'nd groupo'f metallic members Amounted adjacent said other Sends of said barriers for providing a second Yarc path, said barriers being separated 'from .all -said metallic members by air gaps.

` HENRY :REFERENCES 'CI-TED vThe following vreferences are 'of record inthe iil'e 'of this patent:

UNITED STATES PATENTS 

